Yes it says guests can post and they can. Payment is separate thing and in the free version and the pro version, it works only for logged in users. But we are adding some major changes in the next version in the subscription feature with recurring payment and coupon system. Also we are thinking for guest payment feature. Until then, you've to wait. Clearly we don't have any ETA.
It might sound odd, but according to our ToS we don't offer any refund.